Scroll compressor

ABSTRACT

A scroll compressor includes a casing, an electric motor housed in the casing, a drive shaft driven by the electric motor, a compression mechanism, a housing and an oil transfer mechanism. The compression mechanism has movable and fixed scrolls. The movable scroll has an engaging portion engaging one end of the drive shaft. The housing includes a bearing supporting the drive shaft and a receiving portion receiving the engaging portion. The oil transfer mechanism transfers oil in an oil reservoir of the casing. The drive shaft is provided. with an oil supply passage supplying the oil transferred by the oil transfer mechanism to a sliding portion of the engaging portion. The housing is provided with a recess provided on a bottom of the receiving portion and an oil supply channel delivering the oil in the recess to a. sliding portion of the compression mechanism.

TECHNICAL FIELD

The present invention relates to a scroll compressor, and moreparticularly relates to a measure to supply oil to a sliding portion ofa compression mechanism.

BACKGROUND ART

Scroll compressors having a fixed scroll and a movable scroll forcompressing a fluid therebetween have been known and widely used in,e.g., a refrigerating apparatus.

Patent Document 1 discloses a scroll compressor of this type. The scrollcompressor has an electric motor housed in a casing, and a drive shaftdriven in rotation by the electric motor. One end of the drive shaft isengaged with an engaging portion of an end plate of the movable scroll.The rotation of the drive shaft being driven by the electric motorcauses the movable scroll to rotate eccentrically relative to the fixedscroll, which gradually reduces the volume of a compression chamberbetween these scrolls, thereby compressing the fluid in the compressionchamber.

Further, a housing which rotatably receives the drive shaft is fixed tothe inner peripheral surface of the casing. The housing has a receivingchamber, arranged in its upper middle portion, for receiving the driveshaft and the engaging portion of the movable scroll. An oil pump isprovided at a lower end portion of the drive shaft in order to suck upoil from an oil reservoir at the bottom of the casing. The oil sucked upby the oil pump with the rotation of the drive shaft flows upwardthrough an oil passage in the drive shaft. The oil is then supplied to abearing of the drive shaft and the sliding portion between the driveshaft and the engaging portion of the movable scroll, and thereafterinto the receiving chamber. The oil accumulated in the receiving chambersequentially flows through an oil passage 44 a extending radiallyoutward from the receiving chamber, and an oil passage 44 b extendingupward from the outlet of the oil passage 44 a, and is then supplied toa sliding portion (a sliding portion of a thrust surface) of thecompression mechanism. Thus, the scroll compressor of Patent Document 1lubricates the sliding portion of the thrust surface of the compressionmechanism, using the oil which has been used to lubricate the slidingportion between the drive shaft and the engaging portion of the movablescroll.

CITATION LIST Patent Document

Patent Document 1: Japanese Unexamined Patent Publication No,2001-214872

SUMMARY OF THE INVENTION Technical Problem

The scroll compressor disclosed in Patent Document 1 always needs tostore a certain amount of oil in the receiving chamber so that the oilin the receiving chamber can be supplied to the sliding portion of thecompression mechanism with reliability. However, such storage of acertain amount of oil in the receiving chamber will cause the driveshaft or engaging portion housed in the receiving chamber to be soakedin the oil. This increases a frictional resistance between the driveshaft or the engaging portion and the oil during the rotation of thedrive shaft, thereby increasing churning loss and the motive energy ofthe electric motor.

In view of the foregoing background, it is therefore an object of thepresent invention to provide a scroll compressor that can reduce suchoil churning loss in the receiving chamber.

Solution to the Problem

A first aspect of the invention is directed to a scroll compressorincluding: a casing (15); an electric motor (50) housed in the casing(15); a drive shaft (60) driven by the electric motor (50); acompression mechanism (20) which has a movable scroll (40) and a fixedscroll (30), the movable scroll (40) having an engaging portion (43),with which one end of the drive shaft (60) engages, and rotatingeccentrically relative to the drive shaft (60); a housing (25) includinga bearing (28) which supports the drive shaft (60), and a receivingportion (26) which receives the engaging portion (43); and an oiltransfer mechanism (75) which transfers oil in an oil reservoir (18) ofthe casing (15). The drive shaft (60) is provided with an oil supplypassage (70) which supplies the oil transferred by the oil transfermechanism (75) to a sliding portion (44) of the engaging portion (43).In this scroll compressor, the housing (25) is provided with a recess(78) which is provided on a bottom (26 a) of the receiving portion 115(26), and in which the oil accumulates after lubricating the slidingportion (44) of the engaging portion (43), and an oil supply channel(90) which delivers the oil in the recess (78) to a sliding portion (35,45) of the compression mechanism (20).

In the first aspect of the invention, one end of the drive shaft (60)engages with the engaging portion (43) of the movable scroll (40),thereby coupling the drive shaft (60) and the movable scroll (40).Rotation of the drive shaft (60) being driven by the electric motor (50)causes the movable scroll (40) to rotate eccentrically relative to thefixed scroll (30), which reduces the volume of a compression chamberbetween the fixed scroll (30) and the movable scroll (40), therebycompressing the fluid in the compression chamber.

The oil transfer mechanism (75) supplies the oil in the oil reservoir(18) of the casing (15) to the sliding portion (44) between the driveshaft (60) and the engaging portion (43) via the oil supply passage(70). As a result, the sliding portion (44) is lubricated with the oilto cause a decrease in sliding friction. The oil used to lubricate thesliding portion (44) of the engaging portion (43) flows into thereceiving portion (26) that receives the engaging portion (43). Sincethe present invention provides a recess (78) on the bottom of thereceiving portion (26), the oil which has flowed out falls down into therecess (78). This reduces the possibility of the oil accumulating in thereceiving portion (26) so much as to reach the vicinity of the engagingportion (43). As a result, the oil churning loss is reduced at theengaging portion (43) during its rotation.

The oil which has fallen down into the recess (78) is led to the slidingportion (35, 45) of the compression mechanism (20) through the oilsupply channel (90). Since the recess (78) is located at a lower levelthan the bottom of the receiving portion (26), the oil in the receivingportion (26) is successively supplied into the recess (78). This allowsfor a. reliable supply of the oil in the recess (78) to the slidingportion (35, 45) of the compression mechanism (20).

A second aspect of the invention is an embodiment of the first aspect ofthe invention. In the second aspect, the recess (78) is configured as anannular groove (78) surrounding an entire periphery of the bearing (28),

The recess of the second aspect is configured as an annular groove (78)surrounding an entire periphery of the bearing (28) of the drive shaft(60). The annular groove surrounding the entire periphery of the bearing(28) decreases the elastic modulus of a portion of the housing (25)between the annular groove (78) and the bearing (28). Thus, this portionis easily deformed along the outer peripheral surface of the drive shaft(60) even if the axial center of the drive shaft (60) inclines duringthe rotation of the drive shaft (60). This prevents the outer peripheralsurface of the drive shaft (60) from partially contacting with thebearing (28), thereby reducing bearing load on the bearing (28).

A third aspect of the invention is an embodiment of the first or secondaspect of the invention. In the third aspect, the housing (25) isprovided with an oil exhaust channel (80) which delivers the oil in thereceiving portion (26) to the oil reservoir (18).

In the third aspect of the invention, part of the oil which has fallendown into the receiving portion (26) after lubricating the slidingportion (44) of the engaging portion (43) returns to the oil reservoir(18) through the oil exhaust channel (80). This prevents a shortage ofoil in the oil reservoir (18). Further, a rise in the oil level of thereceiving portion (26) is prevented by returning the oil in thereceiving portion (20 to the oil reservoir (18) through the oil exhaustchannel (80). Thus, the engaging portion (43) is prevented from beingsoaked in the oil, which reduces the oil churning loss at the engagingportion (43) during its rotation.

A fourth aspect of the invention is an embodiment of the third aspect ofthe invention. In the fourth aspect, an inlet port (80 a) of the oilexhaust channel (80) is opened to an inner space of the receivingportion (26) so as to be level with the bottom (26 a) of the receivingportion (26).

In the fourth aspect of the invention, the inlet port (80 a) of the oilexhaust channel (80) is arranged to be level with the bottom (26 a) ofthe receiving portion (26). Thus, the oil which has overflowed from therecess (78) is immediately introduced to the oil exhaust channel (80).The rise in the oil level in the receiving portion (26) is thereforeprevented with reliability.

A fifth aspect of the invention is an embodiment of the third aspect ofthe invention. In the fifth aspect, an inlet port (80 a) of the oilexhaust channel (80) is opened to inside of the recess (78).

In the fifth aspect of the invention, part of the oil which has fallendown into the recess (78) from the receiving portion (26) returns to theoil reservoir (18) through the oil exhaust channel (80). Thus, the oilin the recess (78) is prevented from overflowing into the receivingportion (26), thereby preventing the rise in the oil level in thereceiving portion (26) with reliability.

A sixth aspect of the invention is an embodiment of the fifth aspect ofthe invention. In the sixth aspect, the inside of the recess (78) ispartitioned, by a partition member (100) extending from a bottom of therecess (78) to an open end of the recess (78), into a first space (S1)which communicates with an inlet port (90 a) of the oil supply channel(90), and a second space (S2) which communicates with the inlet port (80a) of the oil exhaust channel (80), and the first space (S1) has alarger volume than the second space (S2).

In the sixth aspect of the invention, the inside of the recess (78) ispartitioned into a first space (S1) and a second space (S2) by apartition member (100). The volume of the first space (S1) thatcommunicates with the oil supply channel (90) is larger than the volumeof the second space (52) that communicates with the oil exhaust channel(80). This means that the amount of the oil falling down into the recess(78) after having been used to lubricate the sliding portion (44) of theengaging portion (43) is greater in the first space (S1) than in thesecond space (S2). Thus, the present invention allows for storing asufficient amount of oil to be supplied to the sliding portion (35, 45)of the compression mechanism (20) through the oil supply channel (90).

A seventh aspect of the invention is an embodiment of any one of thethird to sixth aspects of the invention. In the seventh aspect, theinlet port (90 a) of the oil supply channel (90) is located at a lowerlevel than the inlet port (80 a) of the oil exhaust channel (80).

In the seventh aspect of the invention, the inlet port (90 a) of the oilsupply channel (90) is located at a lower level than the inlet port (80a) of the oil exhaust channel (80). Thus, if the oil level is betweenthe inlet port (90 a) of the oil supply channel (90) and the inlet port(80 a) of the oil exhaust channel (80), this oil is led only to the oilsupply channel (90). On the other hand, if the oil level is higher thanthe inlet port (80 a) of the oil exhaust channel (80), this oil is ledto both of the oil supply channel (90) and the oil exhaust channel (80).That is, according to the present invention, the oil which has flowedout into the receiving portion (26) is supplied preferentially to theoil supply channel (90) rather than to the oil exhaust channel (80).This allows for reliable lubrication of the sliding portion (35, 45) ofthe compression mechanism (20).

ADVANTAGES OF THE INVENTION

According to the present invention, the recess (78) is provided on thebottom (26 a) of the receiving portion (26). This allows for deliveringthe oil used to lubricate the sliding portion (44) of the engagingportion (43) to the recess (78). As a result, the possibility of theengaging portion (43) being soaked in the oil is reduced in thereceiving portion (26), thereby reducing the oil churning loss at theengaging portion (43) during its rotation.

If the oil were agitated by the engaging portion (43), a compressedfluid could be mixed with this oil, or the oil might turn into a mist.As a result, it would be difficult for the oil to return to the oilreservoir (18) due to its own weight, causing a shortage of oil in theoil reservoir (18). On the other hand, in the present invention, thepossibility of the engaging portion (43) being soaked in the oil isreduced as mentioned above, which therefore prevents the compressedfluid from being mixed with the oil, and also prevents the oil fromturning into a mist. Thus, the oil used to lubricate the sliding portion(44) can immediately return to the oil reservoir (18), and so-called oilshortage can be prevented.

According to the second aspect of the invention, the recess isconfigured as an annular groove (78). This prevents partial contactbetween the drive shaft (60) and the bearing (28), That is, in thepresent invention, the annular groove (78) functions not only as arecess (78) for accumulating the oil but also as a so-called elasticgroove. This allows for simplifying the device structure.

According to the third aspect of the invention, the oil which has flowedout into the receiving portion (26) returns to the oil reservoir (18)via the oil exhaust channel (80). This prevents the engaging portion(43) from being soaked in the oil, thereby reducing the possibility ofthe oil being agitated by the engaging portion (43). In particular,according to the fourth aspect of the invention, the inlet port (80 a)of the oil exhaust channel (80) is level with the bottom (26 a) of thereceiving portion (26). Thus, the oil in the receiving portion (26) canbe immediately discharged. Further, according to the fifth aspect of theinvention, the inlet port (80 a) of the oil exhaust channel (80) isopened to the inside of the recess (78). This prevents the oil in therecess (78) from overflowing into the receiving portion (26). As aresult, according to the fourth and fifth aspects of the invention, therise in the oil level of the receiving portion (26) is effectivelyprevented, thereby reducing the possibility of the oil being agitated bythe engaging portion (43) with reliability.

According to the sixth aspect of the invention, the inside of the recess(78) is partitioned into a first space (S1) and the second space (S2) bya partition member (100), and the first space (S1) communicating withthe oil supply channel (90) has a larger volume than the second space(S2). This prevents a shortage of the oil to be supplied from the oilsupply channel (90) to the sliding portion (35, 45) of the compressionmechanism (20). As a result, the sliding portion (35, 45) of thecompression mechanism (20) is lubricated successfully, and thereliability of the scroll compressor is improved eventually,

According to the seventh aspect of the invention, the inlet port (90 a)of the oil supply channel (90) is located at a lower level than theinlet port (80 a) of the oil exhaust channel (80). This prevents ashortage of the oil to be supplied from the oil supply channel (90) tothe sliding portion (35, 45) of the compression mechanism (20). As aresult, the sliding portion (35, 45) of the compression mechanism (20)is lubricated as intended, and the reliability of the scroll compressoris improved eventually.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view illustrating the generalconfiguration of a scroll compressor according to an embodiment.

FIG. 2 is a vertical cross-sectional view illustrating, on a largerscale, main parts of a compression mechanism and housing according to anembodiment.

FIG. 3 is a horizontal cross-sectional view illustrating the internalstructure of the compression mechanism.

FIG. 4 is a cross-sectional view taken along the plane X-X of FIG. 2.

FIG. 5 illustrates a scroll compressor of a first variation andcorresponds to FIG. 2.

FIG. 6 is a perspective view illustrating an internal structure of acentral recess in a scroll compressor of a second variation.

FIG. 7 is a horizontal cross-sectional view illustrating the internalstructure of the central recess in the scroll compressor of the secondvariation.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention will now be described in detailwith reference to the drawings. The following embodiment is an onlypreferred example in nature, and is not intended to limit the scope,applications, and use of the invention.

An embodiment of the present invention will be described. A scrollcompressor (10) of the present embodiment is a hermetically sealedcompressor. The scroll compressor (10) is connected to a refrigerantcircuit, which performs a refrigeration cycle, to suck and compress arefrigerant in the refrigerant circuit.

General Configuration for Scroll Compressor

As illustrated in FIG. 1, the scroll compressor (10) has a casing (15)which houses, in its inner space, a compression mechanism (20), anelectric motor (50), a lower bearing member (55), and a drive shaft(60). The casing (15) is a vertically elongated cylindrical hermeticcontainer. The compression mechanism (20), the electric motor (50), andthe lower bearing member (55) are arranged in this order from top tobottom in the inner space of the casing (15). The drive shaft (60) isarranged such that its axial direction is parallel to the heightdirection of the casing (15). The structure of the compression mechanism(20) will be described later in detail.

A suction pipe (16) and a discharge pipe (17) are attached to the casing(15). Both of the suction pipe (16) and the discharge pipe (17) passthrough the casing (15). The suction pipe (16) is connected to thecompression mechanism (20). The discharge pipe (17) is opened to theinner space of the casing (15) between the electric motor (50) and thecompression mechanism (20).

The lower bearing member (55) has a central cylindrical portion (56) andan arm portion (57). Although FIG. 1 illustrates only one arm portion(57), the lower bearing member (55) actually has three arm portions(57). The central cylindrical portion (56) has an approximatelycylindrical shape. Each of the arm portions (57) extends outward fromthe outer peripheral surface of the central cylindrical portion (56).The three arm portions (57) of the lower bearing member (55) are spacedapart from each other at substantially equal angles. Projecting ends ofthe respective arm portions (57) are fixed to the casing (15). A bearingmetal (58) is inserted in the vicinity of an upper end portion of thecentral cylindrical portion (56). An auxiliary journal (67) of the driveshaft (60) to be described later is inserted in, and passes through,this bearing metal (58). The central cylindrical portion (56) functionsas a journal bearing which supports the auxiliary journal (67).

The electric motor (50) has a stator (51) and a rotor (52). The stator(51) is fixed to the casing (15). The rotor (52) is arranged coaxiallywith the stator (51). A main shaft portion (61) of the drive shaft (60)to be described later is inserted in, and passes through, this rotor(52). A plurality of core cuts (51 a) extending between both ends of thestator (51) in its axial direction are formed in the outer peripheralsurface of the stator (51) in order to allow a refrigerant and oil toflow therethrough.

The drive shaft (60) includes the main shaft portion (61), a balanceweight portion (62), and an eccentric portion (63). The balance weightportion (62) is disposed at a halfway point in the axial direction ofthe main shaft portion (61). A portion of the main shaft portion (61)under the balance weight portion (62) passes through the rotor (52) ofthe electric motor (50). Another portion of the main shaft portion (61)over the balance weight portion (62) functions as a main journal (64),and still another portion of the main shaft portion (61) under theportion passing through the rotor (52) functions as the auxiliaryjournal (67). The main journal (64) is inserted in, and passes through,a bearing metal (28) provided inside a central expansion (27) of ahousing (25). The auxiliary journal (67) is inserted in, and passesthrough, the bearing metal (58) provided inside the central cylindricalportion (56) of the lower bearing member (55).

The eccentric portion (63) is arranged at the upper end of the driveshaft (60). The eccentric portion (63) has a columnar shape with asmaller diameter than the main journal (64), and projects from the upperend surface of the main journal (64). The axial center of the eccentricportion (63) is parallel to the axial center of the main journal (64)(i.e., the axial center of the main shaft portion (61)), and iseccentric with the axial center of the main journal (64). The eccentricportion (63) in inserted in a bearing metal (44) provided inside acylindrical portion (43) of the movable scroll (40). The cylindricalportion (43) of the movable scroll (40) functions as an engaging portionwith which the eccentric portion (63) rotatably engages.

The drive shaft (60) is provided with an oil supply passage (70). Theoil supply passage (70) has one main passage (74) and three branchpassages (71-73). The main passage (74) extends along the axial centerof the drive shaft (60). One end of the main passage (74) is opened tothe bottom end of the main shaft portion (61), and the other end thereofis opened to the upper end surface of the eccentric portion (63). Afirst branch passage (71) is provided for the eccentric portion (63).The first branch passage (71) extends outward from the main passage (74)in the radial direction of the eccentric portion (63), and is opened tothe outer peripheral surface of the eccentric portion (63). A secondbranch passage (72) is provided for the main journal (64). The secondbranch passage (72) extends outward from the main passage (74) in theradial direction of the main journal (64), and is opened to the outerperipheral surface of the main journal (64). A third branch passage (73)is provided for the auxiliary journal (67). The third branch passage(73) extends outward from the main passage (74) in the radial directionof the auxiliary journal (67), and is opened to the outer peripheralsurface of the auxiliary journal (67).

An oil supply pump (75), which functions as an oil transfer mechanism,is attached to the lower end of the drive shaft (60). The oil supplypump (75) is a trochoid pump driven by the drive shaft (60). The oilsupply pump (75) is arranged near the starting end of the main passage(74) of the oil supply passage (70). Further, the oil supply pump (75)is provided with an inlet port (76), opened downward at its lower end,for sucking up the refrigeration oil, whish is a lubricating oil. Theoil supply pump (75) does not have to be the trochoid pump but may alsobe any positive displacement pump driven by the drive shaft (60). Thus,the oil supply pump (75) may be a gear pump, for example.

The refrigeration oil, which is a lubricating oil, is accumulated at thebottom of casing (15). That is, an oil reservoir (8) is provided at thebottom of the casing (15). As the drive shaft (60) rotates, the oilsupply pump (75) sucks up the refrigeration oil from the oil reservoir(18) and discharges that refrigeration oil, which then flows through themain passage (74). The refrigeration oil flowing through the mainpassage (74) is supplied to the lower bearing member (55) and thesliding portion between the compression mechanism (20) and the driveshaft (60). Since the oil supply pump (75) is a positive displacementpump, the flow rate of the refrigeration oil in the main passage (74) isproportional to ⁻the rotational speed of the drive shaft (60).

As also illustrated in FIG. 2, in the casing (15), a housing (25) isprovided above the electric motor (50). The housing (25) has a thickdisk-like shape, with its outer peripheral edge fixed to the casing(15). The housing (25) is provided, at its central portion, with acentral recess (26) and an annular projection (29). The central recess(26) is a columnar depression opened on the upper surface of the housing(25). The central recess (26) functions as a receiving portion whichreceives the cylindrical portion (43) of the movable scroll (40) and theeccentric portion (63) of the drive shaft (60). The annular projection(29) surrounds the outer periphery of the central recess (26), andprojects from the upper surface of the housing (25). The projecting endsurface of the annular projection (29) is a flat surface. The projectingend surface of the annular projection (29) is provided with a ring-likerecessed groove along its circumferential direction, A seal member (29a) is fitted in this recessed groove.

The housing (25) has the central expansion (27). The central expansion(27) is located under the central recess (26) and expands downward. Thecentral expansion (27) has a through hole which vertically runs throughthe central expansion (27), and into which the bearing metal (28) isinserted. The main journal (64) of the drive shaft (60) is inserted in,and passes through, the bearing metal (28) of the central expansion(27). The central expansion (27) serves as a journal bearing whichsupports the main journal (64).

Configuration for Compression Mechanism

As also illustrated in FIG. 2, the compression mechanism (20) includesthe fixed scroll (30) and the movable scroll (40). The compressionmechanism (20) is further provided with an Oldham coupling (24) forregulating the rotational movement of the movable scroll (40).

The fixed scroll (30) and the movable scroll (40) are mounted on thehousing (25). The fixed scroll (30) is fixed to the housing (25) with,e.g., a bolt. On the other hand, the movable scroll (40) engages withthe housing (25) via the Oldham coupling (24), and is relatively movablewith respect to the housing (25). The movable scroll (40) engages withthe drive shaft (60) and rotates eccentrically.

The movable scroll (40) is a member comprised of a movable end plate(41), a movable lap (42), and the cylindrical portion (43) which arcformed. integrally with each other, The movable end plate (41) has adisk shape. The movable lap (42) has a spiral wall shape, and protrudesfrom the front surface (the upper surface in FIGS. 1 and 2) of the 115movable end plate (41). The cylindrical portion (43) has a cylindricalshape, and protrudes from the back surface (the lower surface in FIGS. 1and 2) of the movable end plate (41).

The back surface of the movable end plate (41) of the movable scroll(40) is in sliding contact with the seal member (29 a) provided on theannular projection (29) of the housing (25). On the other hand, thecylindrical portion (43) of the movable scroll (40) is inserted in thecentral recess (26) of the housing (25) from over the recess (26), Thebearing metal (44) is inserted in the cylindrical portion (43), andfunctions as a sliding portion with which the eccentric portion (63)comes into sliding contact. The eccentric portion (63) of the driveshaft (60) to be described later is inserted in the bearing metal (44)of the cylindrical portion (43) from under the bearing metal (44). Thecylindrical portion (43) functions as a journal bearing which slidesagainst the eccentric portion (63).

The fixed scroll (30) is a member comprised of a fixed end plate (31), afixed lap (32), and an outer peripheral portion (33) which are formedintegrally with each other. The fixed end plate (31) has a disk shape.The fixed lap (32) has a spiral wall shape, and protrudes from the frontsurface (the lower surface in FIGS. 1 and 2) of the fixed end plate(31). The outer peripheral portion (33) has a thick ring-like shapeextending downward from the fixed end plate (31), and surrounds thefixed lap (32).

The fixed end plate (31) is provided with a discharge port (22), Thedischarge port (22) is a through hole provided around the center of thefixed end plate (31), and runs through the fixed end plate (31) in thethickness direction. Further, the suction pipe (16) is inserted in aportion of the fixed end plate (31) around its the outer periphery.

The compression mechanism (20) is provided with a discharge gas passage(23). The starting end of the discharge gas passage (23) communicateswith the discharge port (22). Although not shown, the discharge gaspassage (23) extends from the fixed scroll (30) to the housing (25), andthe other end thereof is opened to the lower surface of the housing(25).

In the compression mechanism (20), the fixed scroll (30) and the movablescroll (40) are arranged such that the front surface of the fixed endplate (31) and the front surface of the movable end plate (41) face eachother, and that the fixed lap (32) and the movable lap (42) engage witheach other. Such engagement between the fixed lap (32) and the movablelap (42) forms a plurality of compression chambers (21) in thecompression mechanism (20).

Further, in the compression mechanism (20), the movable end plate (41)of the movable scroll (40) and the outer peripheral portion (33) of thefixed scroll (30) are in sliding contact with each other. Moreparticularly, a portion of the front surface (the upper surface in FIGS.1 and 2) of the movable end plate (41) outside the movable lap (42) is asliding portion (45) of a movable thrust surface which comes intosliding contact with the fixed (30). On the other hand, the projectingend surface (the lower surface in FIGS. 1 and 2) of the outer peripheralportion (33) of the fixed scroll (30) comes into sliding contact withthe sliding portion (45) of the movable thrust surface of the provablescroll (40). A portion of the projecting end surface of the outerperipheral portion (33) which is in sliding contact with the slidingportion (45) of the movable thrust surface is a sliding portion (35) ofa fixed thrust surface. That is, the sliding portion (35) of the fixedthrust surface and the sliding portion (45) of the movable thrustsurface form a sliding portion of the compression mechanism (20).

As illustrated in FIGS. 2 and 4, the bottom (26 a) of theabove-described central recess (26) is provided with an annular groove(78). The annular groove (78) is configured as a recess opened upward.The center of the annular groove (78) substantially coincides with theaxial center of the train journal (64), and the annular groove (78)surrounds entirely the bearing metal (28), which is a bearing. Theannular groove (78) may be implemented as a so-called “elastic groove”.That is, the housing (25) is provided with a cylindrical projection (79)projecting upward between the e annular groove (78) and the bearingmetal (28). When the main journal (64) warps radially outward duringrotation of the drive shaft (60), the cylindrical projection (79)elastically deforms along the main journal (64). This prevents the mainjournal (64) from making line contact with the bearing metal (28), i.e.,so-called partial contact, thereby reducing bearing load on the bearingmetal (28).

The oil used to lubricate the bearing metal (28) of the main journal(64) flows through the oil supply passage (70) into the central recess(26) of the housing (25). The housing (25) is provided with ate oilexhaust channel (80) for delivering the oil which has flowed out intothe central recess (26) to the oil reservoir (18), and an oil supplychannel (90) for delivering this oil to the sliding portion (that is,the sliding portion (35) of the fixed thrust surface and the slidingportion (45) of the movable thrust surface) of the compression mechanism(20).

The oil exhaust channel (80) of the present embodiment is provided forthe annular projection (29) of the housing (25). The oil exhaust channel(80) is comprised of a horizontal hole (81) which runs radially througha lower end portion of the annular projection (29), and a vertical hole(82) which extends downward from the outflow end of the horizontal hole(81). An inlet port (80 a) of the oil exhaust channel (80) is opened tothe inside of the central recess (26). The lower portion of the inletport (80 a) of the oil exhaust channel (80) is substantially level withthe bottom (26 a) of the central recess (26). That is, the inlet port(80 a) of the oil exhaust channel (80) is continuous with the bottom (26a) of the central recess (26).

An oil catch plate (83) is arranged under the vertical hole (82) of theoil exhaust channel (80). The oil catch plate (83) has anincreased-width portion (83 a), of which the width increases upward, anda lower nozzle portion (83 b) extending downward from theincreased-width portion (83 a). The outflow end (i.e., the lower end) ofthe lower nozzle portion (83 b) is located in a core cut (51 a) of thestator (51).

The oil supply channel (90) extends from the central expansion (27) tothe annular projection (29) of the housing (25). The oil supply channel(90) is comprised of a first oil supply hole (91) and a second oilsupply hole (92), The first oil supply hole (91) is formed in thehousing (25), and extends radially outward, and obliquely upward, fromthe annular groove (78). An inlet port (91 a) of the first oil supplyhole (91) is opened to the inside of the annular groove (78). The inletport (91 a) of the first oil supply hole (91) is located at a lowerlevel than the inlet port (80 a) of the oil exhaust channel (80).Further, the inlet port (91 a) of the first oil supply hole (91) islocated at a higher level than the bottom of the annular groove (78).This structure prevents waste or any other foreign substances collectedat the bottom of the annular groove (78) from entering the oil supplychannel (90) through the inlet port (91 a), and eventually prevents theoil supply channel (90) from being clogged with such waste or any othersubstances.

The second oil supply hole (92.) runs through the annular projection(29) of the housing (25) in the axial direction so as to communicatewith the outflow end of the first oil supply hole (91). A screw member(93) is inserted in, and passes through, the second oil supply hole(92). The head (93 a) of the screw member (93) closes the lower end ofthe second oil supply hole (92). The screw member (93) narrows the flowpath of the oil in the second oil supply hole (92). That is, the screwmember (93) functions as a pressure reducing mechanism (a throttlemechanism) that reduces the pressure of the oil flowing through thesecond oil supply hole (92).

As illustrated in FIGS. 2 and 3, the outer peripheral portion (33) ofthe fixed scroll (30) is provided with an oil communication passage (94)which communicates with the second oil supply hole (92), and an oilgroove (95) which communicates with the oil communication passage (94).The inflow end of the oil communication passage (94) is connected to thesecond oil supply hole (92) inside the housing (25). The outflow end ofthe oil communication passage (94) is opened to the sliding portion (45)of the movable thrust surface of the movable scroll (40). The oil groove(95) is a recessed groove provided on the sliding portion (35) of thefixed thrust surface of the outer peripheral portion (33), and has aring-like shape surrounding the fixed lap (32). The oil groove (95)communicates with the outflow end of the oil communication passage (94).

Operation

Operation of the scroll compressor (10) will be described.

Operation of Compressing Refrigerant

In the scroll compressor (10), the energization of the electric motor(50) causes the drive shaft (60) to rotate the movable scroll (40).Since the Oldham coupling (24) regulates the rotational movement of themovable scroll (40), the movable scroll (40) does not rotate on its ownaxis but only revolves around.

When the movable scroll (40) revolves around, a low-pressure gasrefrigerant which has flowed into the compression mechanism (20) throughthe suction pipe (16) is sucked into the compression chamber (21) fromaround outer peripheral edges of the fixed lap (32) and the movable lap(42). Further revolution of the movable scroll (40) disconnects thecompression chamber (21) from the suction pipe (16), thereby closing thecompression chamber (21). The compression chamber (21) then moves alongthe fixed lap (32) and the movable lap (42) toward their innerperipheral edges. In the course of this movement, the volume of thecompression chamber (21) gradually decreases, thus compressing the gasrefrigerant in the compression chamber (21).

As the volume of the compression chamber (21) gradually decreases withthe movement of the movable scroll (40), the compression chamber (21)comes to communicate with the discharge port (22) in the end. Therefrigerant compressed in the compression chamber (21) (that is, ahigh-pressure gas refrigerant) flows into the discharge gas passage (23)through the discharge port (22), and is then discharged into the innerspace of the casing (15). In the inner space of the casing (15), thehigh-pressure gas refrigerant discharged from the compression mechanism(20) is once guided to below the stator (51) of the electric motor (50),and then flows upward through a gap between the rotor (52) and thestator (51) and other regions. Thereafter, the high-pressure gasrefrigerant flows out of the casing (15) through the discharge pipe(17).

The high-pressure gas refrigerant discharged from the compressionmechanism (20) circulates through the inner space of the casing (15)under the housing (25), where the pressure is substantially equal to thepressure of the high-pressure gas refrigerant. This means that thepressure of the refrigeration oil accumulated in the oil reservoir (18)in the casing (15), too, is substantially equal to that of thehigh-pressure gas refrigerant.

On the other hand, although not shown, the inner space of the casing(15) over the housing (25) communicates with the suction pipe (16), andhas almost as much pressure as the low-pressure gas refrigerant to besucked into the compression mechanism (20). This means that in thecompression mechanism (20), a space around the outer periphery of themovable end plate (41) of the movable scroll (40), too, has almost asmuch pressure as the low-pressure gas refrigerant.

Oil Supply Operation at Sliding Portion

During the operation of the scroll compressor (10), the rotating driveshaft (60) drives the oil supply pump (75), thereby sucking up therefrigeration oil accumulated at the bottom of the casing (15) to themain passage (74) of the oil supply passage (70). Part of therefrigeration oil flowing through the main passage (74) flows into thebranch passages (71-73), and the rest flows out of the main passage (74)through its upper end. The oil (the refrigeration oil) which has flowedinto the third branch passage (73) is supplied to a gap between theauxiliary journal (67) and the bearing metal (58), and is used tolubricate and cool the auxiliary journal (67) and the bearing metal(58). The oil which has flowed into the second branch passage (72) issupplied to a gap between the main journal (64) and the bearing metal(28), and is used to lubricate and cool the main journal (64) and thebearing metal (28).

The oil which has flowed into the first branch passage (71) is suppliedto a gap between the eccentric portion (63) and the bearing metal (44),and is used to lubricate and cool the eccentric portion (63) and thebearing metal (44). The oil used to lubricate the bearing metal (44)flows out into the central recess (26).

If this oil used to lubricate the bearing metal (44) is accumulated inthe central recess (26), the cylindrical portion (43) of the movablescroll (40) may be soaked in the oil. If the cylindrical portion (43)performs the eccentric rotational movement a number of times in such astate, the oil in the central recess (26) constitutes a resistance tothe cylindrical portion (43), and so-called oil churning loss increases.This leads to an increase in motive energy of the electric motor (50).Further, if the oil in the central recess (26) is agitated by thecylindrical portion (43), the high-pressure gas refrigerant in thecasing (15) may be mixed with the oil, or the oil may turn into a finemist. As a result, after all, it becomes difficult for the oil agitatedin the central recess (26) to go back to the oil reservoir (18) due toits own weight. This causes a shortage of oil in the oil reservoir (18).The present embodiment therefore provides the annular groove (78) on thebottom (26 a) of the central recess (26) to prevent the oil in thecentral recess (26) from being agitated by the cylindrical portion (43).

More particularly, the refrigerant which has been used to lubricate thebearing metal (44) and flowed into the central recess (26) falls downinto the annular groove (78) from the bottom (26 a) of the centralrecess (26). When the oil level in the annular groove (78) exceeds thelevel of the inlet port (90 a) of the first oil supply hole (91), theoil in the annular groove (78) flows into the first oil supply hole(91). This oil passes through the first oil supply hole (91), and thenflows upward through the second oil supply hole (92). In the course ofthis flow, the high-pressure oil is decompressed in the second oilsupply hole (92) by the screw member (93). The oil which has passedthrough the second oil supply hole (92) flows into the oil groove (95)via the oil communication passage (94) inside the fixed scroll (30). Asa result, the sliding portion of the compression mechanism (20) betweenthe sliding portion (35) of the fixed thrust surface and the slidingportion (45) of the movable thrust surface is lubricated with the oil.

As described above, the oil which has flowed out into the central recess(26) is appropriately supplied to the sliding portion of the compressionmechanism (20) through the annular groove (78) and the oil supplychannel (90). As a result, the rise in the oil level in the centralrecess (26) is prevented, thereby reducing the area of the cylindricalportion (43) of the movable scroll (40) to be soaked iii the oil.

Further, if the oil level in the annular groove (78) rises so much as tomake the oil overflow from the annular groove (78) into the centralrecess (26), this oil flows into the oil exhaust channel (80), In theoil exhaust channel (80), the oil sequentially flows through thehorizontal hole (81), the vertical hole (82), and the oil catch plate(83) to be guided into the core cut (51 a). The oil in the core cut (51a) further flows down along the inner peripheral surface of the casing(15), and is delivered to the oil reservoir (18) in the end.

In this manner, the oil which has overflowed from the annular groove(78) returns directly to the oil reservoir (18) through the oil exhaustchannel (80). Thus, the rise in the oil level in the central recess (26)is prevented, thereby reducing the area of the cylindrical portion (43)of the movable scroll (40) to be soaked in the oil.

Advantages of Embodiment

In the embodiment described above, the annular groove (78) is providedon the bottom (26 a) of the central recess (26) of the housing (25),which allows the annular groove (78) to catch the oil used to lubricatethe bearing metal (44). This reduces the possibility of the cylindricalportion (43) of the movable scroll (40) being soaked in the oil in thecentral recess (26), thereby reducing the oil churning loss at thecylindrical portion (43) during its rotation. As a result, the motiveenergy of the electric motor (50) is reduced, which contributes toenergy saving more effectively.

In addition, since this structure prevents the cylindrical portion (43)from agitating the oil in this manner, it also prevents a compressedfluid from being mixed with the oil, and further prevents the oil fromturning into a mist. Thus, the oil used to lubricate the bearing metal(44) can immediately return to the oil reservoir (18), and thereforeso-called oil shortage is eliminated.

Furthermore, in the embodiment described above, the annular groove (78)is provided around the bearing metal (28) of the main journal (64),which allows for providing the cylindrical projection (79) between theannular groove (78) and the bearing metal (28). This structure allowsthe cylindrical projection (79) to be elastically deformed along themain journal (64) even if the main journal (64) inclines with respect tothe axial center. Thus, the main journal (64) is prevented frompartially contacting with the bearing metal (28), thereby reducingbearing load on the main journal (64). The annular groove (78) functionsnot only as a groove which catches and delivers the oil to the oilsupply channel (90) but also as a so-called elastic groove. This allowsfor simplifying the structure of the housing (25).

On top of that, according to the embodiment described above, part of theoil which has flowed out into the central recess (26) returns directlyto the oil reservoir (18) through the oil exhaust channel (80). Thisprevents the cylindrical portion (43) from being soaked in the oil. Inparticular, according to the present embodiment, the inlet port (80 a)of the oil exhaust channel (80) is arranged to be level with the bottom(26 a) of the central recess (26). Thus, even when the oil overflowsfrom the annular groove (78), this oil can be immediately introduced tothe oil exhaust channel (80).

Furthermore, according to the embodiment described above, the inlet port(90 a) of the oil supply channel (90) is opened to the inside of theannular groove (78), and the inlet port (80 a) of the oil exhaustchannel (80) is opened to the inside of the central recess (26). Thatis, the inlet port (90 a) of the oil supply channel (90) is located at alower level than the inlet port (80 a) of the oil exhaust channel (80).Thus, the oil which has flowed out into the central recess (26) isintroduced to the oil supply channel (90) earlier than to the oilexhaust channel (80). This allows for supplying the oil to the slidingportions (35, 45) of the compression mechanism (20) successfully, andincreases reliability of the scroll compressor (10).

First Variation of Embodiment

The scroll compressor (10) according to a first variation illustrated inFIG. 5 is different from the above embodiment in e configuration of theoil exhaust channel (80). Specifically, the inlet port (80 a) of the oilexhaust channel (80) of the first variation is opened to the inside ofthe annular groove (78). More particularly, the oil exhaust channel (80)has a horizontal hole (81) which extends radially outward from insidethe annular groove (78), and a vertical hole which extends downward fromthe radially outer end of the horizontal hole (81). In the annulargroove (78), the inlet port (90 a) of the oil supply channel (90) islocated at a lower level than the inlet port (80 a) of the oil exhaustchannel (80).

In the first variation, the oil is introduced to the oil supply channel(90) preferentially if the oil level in the annular groove (78) islocated at a level between the inlet port (90 a) of the oil supplychannel (90) and the inlet port. (80 a) of the oil exhaust channel (80).However, when the oil level in the annular groove (78) reaches the levelof the inlet port (80 a) of the oil exhaust channel (80), the oil isintroduced to both of the oil supply channel (90) and the oil exhaustchannel (80). Thus, in the first variation, too, the oil which hasflowed out into the central recess (26) is introduced to the oil supplychannel (90) earlier than to the oil exhaust channel (80). This allowsthe oil to be supplied to the sliding portions (35, 45) of thecompression mechanism (20) successfully, and increases the reliabilityof the scroll compressor (10).

Further, in the first variation, the oil in the annular groove (78) isprevented from overflowing into the central recess (26), since the oilin the annular groove (78) is delivered to both of the oil supplychannel (90) and the oil exhaust channel (80). As a result, thecylindrical portion (43) of the movable scroll (40) is more reliablyprevented from being soaked in the oil.

The other functions and effects of the first variation are the same asthose of the embodiment described above.

Second Variation of Embodiment

The second variation illustrated in FIGS. 6 and 7 includes a housingwhich has a similar configuration to the counterpart of the firstvariation but which includes a partition member (100) in the annulargroove (78). The partition member (100) extends from a lower bottom ofthe annular groove (78) to an upper open end of the annular groove (78)in the axial direction of the annular groove (78). The partition member(100) has an approximately U-shaped cross-section on a planeperpendicular to the axial direction of the annular groove (78), and isfitted in the annular groove (78).

The partition member (100) has an arc-shaped vertical wall (100 a) whichis curved along the inner peripheral surface of the annular groove (78),and a pair of side-walls (100 b) which are located at both ends of thevertical wall (100 a) in its circumferential direction. The verticalwall (100 a) is arranged to face the inlet port (80 a) of the oilexhaust channel (80).

Each of the sidewalls (100 b) extends in a radial direction from theinner peripheral surface to the outer peripheral surface of the annulargroove (78). This partition member (100) partitions the inside of theannular groove (78) into a first space (S1) outside the partition member(100), and a second space inside the partition member (100). The inletport (90 a) of the oil supply channel (90) communicates with the firstspace (S1). The inlet port (80 a) of the oil exhaust channel (80)communicates with the second space (S2),

In the second variation, the opening area of the upper end of the firstspace (S1) is larger than the opening area of the upper end of thesecond space (S2). That is, the volume of the first space (S1) is largerthan the volume of the second space (S2) inside the annular groove (78).Thus, in the second variation, the oil which has flowed out into thecentral recess (26) flows down more into the first space (S1) than intothe second space (S2), thus making it possible to store a sufficientamount of oil in the first space (S1). This allows the oil to besupplied to the sliding portions (35, 45) of the compression mechanism(20) via the first space (S1) and the oil supply channel (90)successfully, and increases the reliability of the scroll compressor(10).

The other functions and effects of the second variation are the same asthose of the above embodiment,

Other Embodiments

The embodiment described above may be modified to have the followingconfigurations.

In the above embodiment, the bottom (26 a) of the central recess (26) isprovided with an annular recess (78) which surrounds the main journal(64). However, this recess (78) does not necessarily have an annularshape, but may have a rectangular, linear, or dotted cross-section on aplane perpendicular to the axial direction. That is, the recess (78) mayhave any shape as long as it is capable of catching the oil flowing outinto the central recess (26).

INDUSTRIAL APPLICABILITY

As can be seen from the foregoing description, the present inventionrelates to a scroll compressor, and is particularly useful for providingan effective measure to supply oil to a sliding portion of a compressionmechanism.

DESCRIPTION OF REFERENCE CHARACTERS

-   10 scroll compressor-   15 casing-   18 oil reservoir-   20 compression mechanism-   25 housing-   26 central recess (receiving portion)-   26 a bottom-   28 bearing metal (bearing)-   30 fixed scroll-   35 sliding portion of fixed thrust surface-   40 movable scroll-   43 cylindrical portion (engaging portion)-   44 bearing metal (sliding portion)-   45 sliding portion of movable thrust surface-   50 electric motor-   60 drive shaft-   70 oil supply passage-   75 oil supply pump (oil transfer mechanism)-   78 annular groove (recess)-   80 oil exhaust channel-   80 a inlet port (on the oil exhaust channel side)-   90 oil supply channel-   90 a inlet port (on the oil supply channel side)-   100 partition member-   S1 first space-   S2 second space

1. A scroll compressor, comprising: a casing; an electric motor housedin the casing; a drive shaft driven by the electric motor; a compressionmechanism having a movable scroll and a fixed scroll, the movable scrollhaving an engaging portion with which one end of the drive shaftengages, and the movable scroll rotating eccentrically relative to thedrive shaft; a housing including a bearing supporting the drive shaft,and a receiving portion receiving the engaging portion; and an oiltransfer mechanism transferring oil in an oil reservoir of the casing,the drive shaft being provided with an oil supply passage supplying theoil transferred by the oil transfer mechanism to a sliding portion ofthe engaging portion, and the housing being provided with a recessprovided on a bottom of the receiving portion, the oil accumulating inthe recess after lubricating the sliding portion of the engagingportion, and an oil supply channel delivering the oil in the recess to asliding portion of the compression mechanism, the recess beingconfigured as an annular groove surrounding an entire periphery of thebearing.
 2. (canceled)
 3. A scroll compressor comprising: a casing; anelectric motor housed in the casing; a drive shaft driven by theelectric motor; a compression mechanism having a movable scroll and afixed scroll, the movable scroll having an engaging portion with whichone end of the drive shaft engages and the movable scroll rotatingeccentrically relative to the drive shaft; a housing including a bearingsupporting the drive shaft, and a receiving portion receiving theengaging portion; and an oil transfer mechanism transferring oil in anoil reservoir of the casing, the drive shaft being provided with an oilsupply passage supplying the oil transferred by the oil transfermechanism to a sliding portion of the engaging portion, and the housingbeing provided with a recess provided on a bottom of the receivingportion. the oil accumulating in the recess after lubricating thesliding portion of the engaging portion, an oil supply channeldelivering the oil in the recess to a sliding portion of the compressionmechanism, and an oil exhaust channel delivering the oil in thereceiving portion to the oil reservoir, an inlet port of the oil exhaustchannel being opened to an inside of the recess.
 4. (canceled) 5.(canceled)
 6. The scroll compressor of claim 3, wherein the inside ofthe recess is partitioned, by a partition member extending from a bottomof the recess to an open end of the recess, into a first space whichcommunicates with an inlet port (90 a) of the oil supply channel and asecond space which communicates with the inlet port of the oil exhaustchannel, and the first space has a larger volume than the second space.7. (canceled)